SSRS drill through - not passing last parameter

SSRS is not passing the last parameter in my drill through report...the first two work fine, but the 3rd requires me to select from the defined Available Values.  For some reason SSRS seems to be ignoring the value being passed for this 3rd parameter.  Omit is set to False on all 3 parameters, and the child report does not have any defined Default values.  Any suggestions?

Below is a portion of the .rdl file for reference:

                        <Style>
                          <TextAlign>Center</TextAlign>
                        </Style>
                      </Paragraph>
                    </Paragraphs>
                    <rd:DefaultName>BusinessSection1</rd:DefaultName>
                    <ActionInfo>
                      <Actions>
                        <Action>
                          <Drillthrough>
                            <ReportName>DetailBySection</ReportName>
                            <Parameters>
                              <Parameter Name="Method">
                                <Value>=Fields!Method.Value</Value>
                              </Parameter>
                              <Parameter Name="Section">
                                <Value>=Fields!BusinessSection.Value</Value>
                              </Parameter>
                              <Parameter Name="DateRangeType">
                                <Value>=Fields!DateRangeType.Value</Value>   ***this value is not being passed***
                              </Parameter>
                            </Parameters>
                          </Drillthrough>
                        </Action>
                      </Actions>
                    </ActionInfo>
                    <ToolTip>Click to View Detailed Report</ToolTip>